Method of making a protected metal article



July 5, 1955 D. s. HUBBELL. 2,712,174

METHOD OF MAKING A PROTECTED METAL ARTICLE Original Filed Sept. 9, 195o24 JNVENToR.

y DEA/Y J. /z/fu.

METHOD oF MAKING A PROTECTED kMETAL ARTICLE Dean S. Hubbell,`Pittsburgh, Pa.,.assignor to H.V H. Robertson Company, Pittsburgh, Pa.,a corporation of Pennsylvania Original application September 9, 1950,Serial No. 184,059, now Patent No.- 2,668,348, :dated February 9, 1954.Divided and this application October 9,1951, Serial No. 250,426

3 Claims. '(Cl. 29-473t1) This invention relates to a protected metalarticle and a method of making the same.

One object of the invention is to produce a novel and superior protectedmetal article of the general type disclosed in the United States Patentsto Coffman' Nos. 1,862,332 and 2,073,334 and in the Unitedl StatesPatent to Robertson No. 1,195,090, and in particular to provide aprotected metal article of such type in which the tendency of thefibrous layers in the article to delaminate is reduced to a minimum,thereby to impart additional life and durability to the article `in use.

Another object of the invention is to provide a novel and superiorconstruction of fibrous sheet' and particularly of felt adapted `for usein producing the protectedmetal articles above lreferred to,l which ischaracterized by superior resistance to delamination.

With these general objects in view and such others as may hereinafterappear, the invention consists-in 'the protected rnetal article and inthe improved fibrous sheety and felt hereinafter described andparticularly defined in the claims at the end of this specification.

In the drawing I have illustrated the; invention as embodied in aprotected metal articlewherein Fig. l is a plan and Fig. 2 a section onthe line 2--2 of Fig. l of the protected metal article.'

As illustrated in the patents to Coffman and Robertson, above referredto, a protected metal article, and particularly a protected steel sheet,suitable for use as a building sheet for roofing and siding purposescomprises a core sheet of steel to which fibrous sheets, suchas asbestosfelt, are secured by a metal adhesive as disclosed in the vCofimanpatents, or by a layer of bituminous material, such as asphalt, asdisclosed in the Robertson patent. The fibrous layer is preferably thussecuredto each `side of the metal sheet, and in practice, the laminatedassembly is preferably enveloped within an outer weatherproofng coatingf of bituminous material. Such protected metalsheets have been usedextensively for roofing and siding purposes all over the world.

The success of theprotective coatingsiand-layers in resisting theweather and corrosive atmospheric conditions depends to a large extentupon the maintenance of the protective material about the ysteelcoresheet, and one of the difficulties which is at times experiencedinthe handling, shipping, and erection of the protected metal buildingsheets flows from the structure -of the asbestos felt, which ispreferably used as the fibrous ylayers in lthe production of theprotected metal sheet. facture of the asbestos felt a substantial butminor amount of an organic binding material, usually wood fiber, isutilized to assist in binding together thev asbestos bers to form thefelt. The character of the asbestos `fiber is such as to preclude theformation of a true felt in the stricter sense ofthe word inasmuch `astheasbestosfibers are not held together by a mechanism by which a realfelt is produced. In other words, in the manufacture of asbestos feltthere lis no real felting of the fibers, and reliancevis placed tocalarge extent on the presence ofthe In the manu- 4'of relatively smallareas.

,a ICC organic materials, such as wood pulp and fiber in order to hold`the laminations of the asbestos felt together.

From 'a consideration of the disclosures in the Coffman patents it: willbe' appreciated that the contact of the asbestos felt with the extremelyhot and molten zinc coating. when the asbestos felt is being attachedand bonded to the` steel core sheet by the interposed layer of lzinc asthe metal adhesive produces a weakening to someextent of they bondingeffect of the organic materials within the asbestos felt. In someinstances the organic materialsare actuallyfcharred, and as a result theresistance of the asbestos felt to delamination is not as great as isdesired. During the handling, and particularly the shipment of therelatively heavy protected metal sheets slight adhesion of adjacentsheets being shipped is oftentimes sufiicient to effect somedelamination of the asbestos felt. Another instance of this difficultyoccurs if there are any stresses in the outer weatherproofing coating,such as stresses set up by the drying out or contraction thereof, theeffect of which is a tendency to lift off some of the laminations of thefelt.`

During the manufacture of the protected metal article, inlaccordancewith the Robertson patent it .has been found desirable to reinforce thefelt by saturations with asphaltic saturants, and while these assist tosome slight `degree vin imparting additional bond between thelaminations of the asbestos felt, the saturants themselves do notpossess sufficient strength to resist delamination under the conditionsusually experienced in shipping, handling, and weathering ofthecommercial metal building sheets.

It -has been recognized that these diiiiculties inherent inasbestos feltcould be overcome by saturating the ,felt

.with ya saturating material which upon cooling or drying,

or .in thecase of resins upon polymerization, possessed relatively highstrength. In this manner, it would be possible tobond theV laminationsof the felt securely together with sufficient strength so that thecommercial delaminating difficulties might be overcome. However, all ofthe available saturating materials possessing the required strength aretoo expensivefor commercial use, and more importantly their use as anall-over saturant ,for the asbestos feltingsl would produce a relativelystiff felt, and inasmuch as most of the building sheets are required tobe corrugated or deformed into special shapessuch relatively stiff feltwould crack during such deformation, thus destroying the protectingqualities of the coatings and layers which have been used in the attemptto form a successful protection for the inner core sheet of theprotected metal sheet. The present invention contemplates saturation ofthe vasbestos felt in a discontinuous manner instead of in an overall orcontinuous manner. Preferably, I prefer to apply to the fibrous sheet ahigh-strength saturant in the form of a uniform pattern These smallareas form in effect strong rivetswhich successifully overcome thetendency of the asbestos felt to be delaminated, and overcome thedifficulties in this respect, above referred to. It has been f ound thatwhen such a fibrous sheet is used lin producing a protected metal sheetin the manner described in either the Coffman or Robertson patents abovereferred to, the protected metal sheet may be successfully corrugatedand deformed without any-liability or crack-l vstrength saturant wasfound to avoid the production of `excessive stiffness in the-saturatedfelt.

In addition, the marked reduction in the amount of saturant applied forav-given area of-,the building sheet enables kthe more`v costlysaturatingvmaterials to beused without destroying,the-competitive.commercial aspectof the product.

For example, if the saturant is applied in areas approximating 1/1@ ofaninchfin diameter Vin a uniform pattern in which the areas were spacedapart on, say, 1A centers over the entire area of the asbestos felt,then only about 5% of the area would be covered, and correspondinglyonly about 5% as much saturant would be required as that necessary tocover the entire sheet. This 5%, however, is effective in stoppingdelamination inasmuch as the small spots of saturant being in themselvesrelatively strong act like the through-ties that are used in quiltingoperations. Any of they known high-strength organic or inorganicsaturants may be used, and the requirements are that the saturatingmaterial should be such as may be easily applied in the desired patternand of a materialsuch that it may be made to strike through thelaminations of the felt. The residue left in theV felt must effectivelybind the asbestos fibers, and either-'be impermeable to moisture oreasily subsequently saturated -with a waterproofing material, such asthe asphaltic saturants heretofore employed. Preferably, .the nature ofthe saturanfs is such as to enable outer bituminous weatherproongcoatings to adhere to it without showing the saturating pattern, andwhen the protected metal sheet is made in accordance with the Coffmanpatents the saturant should not interfere with the bond` of the asbestosfelt to the metal adhesive.

Among the saturants which have been successfully used are solutions ofphenol-formaldehyde resins, and other high-strength resins inappropriate solvents, and as illustrative of the inorganic saturants Ihave found that solutions of silicates, such, for example, as sodium,potassium and ethyl silicates, are suitable.

In practice, I prefer to apply the saturant to the felt prior to itsincorporation into the protected metal article by passing the felt overembossing rolls to which a satu- -rant has been applied. Thenby passingthe felt through heated rolls the saturant is driven through the entirethickness of the felt and this operation eliminates the solvent andpolymerizes the saturant, as in the case of the phenolic resinsreferred, or other resins which -may be used. In the case of thesilicates the heating appears to promote some reaction with the asbestoseffecting a strong rivet-like bond which successfully resistsdelamination.

'Referring now to the drawings, 10 represents a protected metal articlecomprising a steel sheet 12 having secured to the opposite surfacesthereof layers 14- of fibrous material, such as asbestos felt, by aninterposed metal adhesive, such as galvanizing coating 16. This productmay comprise the product disclosed in the Coffmanpatents above referredto. As shown in Fig. 1, the improved felt layer 14 is reinforced by ahigh-strength saturant applied in a pattern of spaced spots or points 18iarranged to extend or penetrate through the fibers of ythe felt andserving to bind the fibers together toprovide a felt web having superiorresistance to delamination .and capable of flexing or being deformedwithout cracking.

In practice, the bonding saturant may be applied in liquid form in thedesired pattern to provide a series of spaced droplets 20 of thesaturant on the surface of a web of felt to be reinforced as illustratedin Fig. 3, and thereafter application of heat and pressure will effectdriving or penetration of the saturant through the web to produce thereinforced web illustrated in Fig. 4.

` As diagrammatically illustrated in Fig. 5, a preferred form ofapparatus for producing the present reinforced `felt may include anembossing or printing roll 22 ar- 'ranged to cooperate with a lower roll24 and having a series of radially arranged and spaced protuberances 26disposed to correspond to the desired pattern. The felt 'web may belwithdrawn from a supply'roll 28 thereof,

passed around a guide roll 30, and then between the rolls 22, 24. Theprinting roll 22 may be provided with the to prevent delamination.

, to the printing roll is transferred to the surface of the web in theform of spots ,or droplets 20, as indicated. Thereafter, the web may bepassed between heated rolls 38, 40 to effect penetration of the saturantthrough the entire thickness of the felt, whereupon the web may passaround a second guide roll 42 andl be wound upon a rewinding roll 44, asillustrated in'Fig. 5. While the abovedescribed method of applying thesaturant has been found satisfactory, it will beapparent that othermethods may be employed, such a'sv by the1 useof hollow needles toeffect application of the spots or droplets 20 on the surface of theweb.

In practice, when the bonding saturant comprises a phenolic orotherresin in a suitable solvent, the passage of the web through the heatedrolls eliminates the solvent and polymerizes the saturantthe residuefirmly bonding the fibers at the saturated points, and likewise, whenthe saturant comprises solutions of silicates, the saturant appears topromote some reaction with the asbestos fibers, thus producing a fibrousweb having superior resistance to` delamination.

While it is not intended to limit the disposition, size, vor spacing ofthe spots of saturant in the fibrous web, it has been found in practicethat good results may be obtained by an application of saturant atspaced` points amounting to only five percent of the area of the web,such proportion being substantially maintained when the spots ofsaturant are approximately one-sixteenth in diameter and spacedone-quarter of an inch apart. Thus, the amount of saturant usedcorrespondingly amounts to only five percent of the saturant which wouldbe required to cover the entire web, such five percent being effectiveIt will be apparent, however, that such proportions may vary over a widerange to produce the desired results.

p In practice, the protected metal article 10 comprising the steel sheet12 provided with the asbestos felt layers 14 afxed thereto by a metaladhesive 16 may be further treated by the application of an asphaltimpregnant or saturant, and thereafter in order to further protect themetal article against weather conditions, fumes, or the like, thecomposite sheet may be provided with an outer bituminous weatherproofcoating, as illustrated and described in the Coffman Patent No.2,073,334. The present bonding saturant applied to the web at spacedpoints in accordance with the present invention does not interfere withthe bond of the felt to the zinc-coated steel, and does not affect theability of the remaining asbestos web to .absorb the asphalt.Furthermore, the outer bituminous coating will adhere to the relativelysmall high-strength saturated areas as readily as to the remaining areasof the asbestos web and without showing the pattern of the saturatedpoints.

The asbestos felt layers provided with the high-strength spotsaturations as .above described may be used with subject matter of theRobertson and Coffman patents above referred to and maybe used withadvantage for all of the purposes for which such protected metal sheetsand I \articles may lbe used. 7n This application is a division of myapplication Serial required saturant by an applying roll 32 cooperatingwith No. 184,059 filed September 9, i950, for Protected Metal Articleand Method of Making the Same, now Patent While the preferredembodiments of theinvention have -been herein illustrated and described,it will be understood that the invention may be embodied in other formswithin the scope of the following claims.

Having thus described the invention, what is claimed 1. The method ofmaking a protected metal sheet fcr building purposes which consists inapplying to the surface of a laminable fibrous web a plurality ofuniformly spaced, individual droplets of a liquid, high-strengthsaturant; then simultaneously applying heat and pressure to oppositesides of lsaid web thereby driving said saturant through the entirethickness of said web to form individual spots of high-strength saturantbinding the iibers of said web against delamination, while maintainingthe spacing of said individual spots so that the combined areas of saidspots constitute only a small fraction of the total area of said web;and then adhesively aixing the spot saturated web to a metal sheet by ametal adhesive.

2. The method defined in claim 1 wherein the web after it has been spotsaturated with the high-strength saturant, is then saturated with alow-strength flexible waterproofing saturant to saturate the portions ofthe web between said spots.

3. The method of making a protected metal sheet for building purposeswhich consists in applying to the surface of a laminable fibrous web aplurality of uniformly spaced, individual droplets of a liquid,high-strength saturant arranged in rows substantially transversely ofsaid web to leave the entire'portions of said web between adjacenttransverse rows of said droplets free of said highstrength saturant;then simultaneously applying heat and pressure to opposite sides of saidweb thereby driving said saturant through the entire thickness of saidweb to form individual spots of high-strength saturant binding thefibers of said web against delamination, while maintaining the spacingof said individual spots so that the com# bined areas of said spotsconstitute only a small fraction of the total area of said web; and thenadhesively affixing the spot saturated web to a metal sheet by a metaladhesive, the application of droplets of said high-strength saturant inrows substantially transversely of said web permitting flexure of theweb without cracking after driving through and setting of saidhigh-strength saturant by heat and pressure.

References Cited in the le of this patent UNITED STATES PATENTS1,195,090 Robertson Aug. 15, 1916 1,863,186 Burns June 14, 19322,087,064 McMillan July 13, 1937 2,154,943 King Apr. 18, 1939 2,177,425Barker Oct. 24, 1939 2,207,279 Alderfer July 9, 1940 2,545,952 GoldmanMar. 20, 1951 2,668,348 Hubbell Feb. 9. 1954

1. THE METHOD OF MAKING A PROTECTED METAL SHEET FOR BUILDING PURPOSESWHICH CONSISTS IN APPLYING TO THE SURFACE OF A LAMINABLE FIBROUS WEB APLURALITY OF UNIFORMLY SPACED, INDIVIDUAL DROPLETS OF A LIQUID,HIGH-STRENGTH SATURANT; THEN SIMULTANEOUSLY APPLYING HEAT AND PRESSURETO OPPOSITE SIDES OF SAID WEB THEREBY DRIVING SAID SATURANT THROUGH THEENTIRE THICKNESS OF SAID WEB TO FORM INDIVIDUAL SPOTS OF HIGH-STRENGTHSATURANT BINDING THE FIBERS OF SAID WEB AGAINST DELAMINATION, WHILEMAINTAINING THE SPACING OF SAID INDIVIDUAL SPOTS SO THAT THE COMBINEDAREAS OF SAID SPOTS CONSTITUTE ONLY A SMALL FRACTION OF THE TOTAL AREAOF SAID WEB; AND THEN ADHESIVELY AFFIXING THE SPOT SATURATED WEB TO AMETAL SHEET BY A METL ADHESIVE.